Fuel supply means for engines



July 3, 1962 E. 1.. NELSON 3,042,013 FUEL SUPPLY MEANS FOR ENGINES FiledSept. 12, 1960 IN V EN TOR. EU6E'NE 4. N51. 50!

A Tree/v5 Y5 States atent Office 3,042,013 Patented July 3, 19623,042,013 FUEL SUPPLY MEANS FOR ENGINES Eugene L. Nelson, Cedarburg,Wis., assignor to Tecumseh Products Co., Tecumseh, Mich., a corporationof Michigan Filed Sept. 12, 1960, Ser. No. 55,334 4 Claims. (Cl. 123-73)The present invention relates generally to improvements in crankcaseinduction of fuel for internal combustion engines, and relates moreparticularly to improvements in fuel supply valves for controlling thedelivery of fuel mixture to the crankcase of engines of the fractionalhorsepower type.

A primary object of the invention is to provide improved valve means forthe introduction of fuel to the crankcases of small horsepower internalcombustion engines, whereby the engine will operate at high speed and atmaximum volumetric efficiency.

Various types of inspiration or induction devices for admittingsuccessive charges of fuel mixture to one or more cylinders offractional horsepower type internal combustion engines through thecrankcase or crankcases have heretofore been proposed and usedextensively. In some of these prior fuel admission devices, theintroduction of the fuel mixture into each crankcase is effected as bymeans of one or two reed type valves formed on a flat apertured plateattached to the fuel inlet line at its opening into the crankcasechamber below the piston. The valves in such a device commonly consistof a flexible reedplate covering the opening and adapted to flex orswing toward the crankcase chamber to direct the charge more orlesslaterally into the chamber. While such reed plate assemblies have beenextensively used, they have neverthelesspossessed certain objectionsparticularly with regard to. efliciency of operation, effective mixingand direction of fuel and relatively slow and restricted deliverythereof to the chamber. Furthermore, the restricted number of inletapertures and reed type admission valves accommodated by the usual reedplate places eachsuch valve under heavy duty at all times, and failureof one of the reeds to perform its function properly is immediatelyapparent and exaggerated in the engines operation.

In other instances, fuel induction devices of various shapes and sizeshave been proposed in efforts to increase the number of inlet openingsand reed valves and to so position the valves as to more effectivelydeliver the fuel and air mixture to the crankcase chamber in order toimprove volumetric efliciency and mixture. One of these valveassemblages is in the general form or'shape of a pyramid in whichopenings are provided on the four sides, the openings being covered bythe usual flexible reeds directed toward the crankcase chamber so as todeliver the fuel and air mixture in a relatively flat stream toward thepiston rather than laterally into the crankcase chamher as in priordevices of the flat plate type. While such pyramidal-shaped reed Valveassemblages have resulted in somewhat improved engine performance, thevolumetric efficiency and engine operation has still left something tobe desired.

It is therefore another object of the present invention to provide areed-type valve assemblage for fractional horsepower internal combustionengines which obviates the objections and disadvantages of prior devicesof this general type.

Another object of this invention is to provide a fuel supply orinduction device incorporating a maximum number of reed valves which arecompactly nested. and which provide an extensive fuel supply to thecrankcase.

A further object of the invention is to provide a reed valve assemblagefor use in controlling the supply of fuel mixture to the crankcase of aninternal combustion engine in which the reed valves are most eflicientlylocated so as to direct the mixture with maximum efliciency to thecrankcase chamber at one end of the piston.

An additional object of the invention is to provide a crankcase fuelinjection device for internal combustion engines in which thepossibility of valve breakage is minimized by limiting the swingingmotion of the individual reed valves in predetermined directions.

Still another object of my present invention is to provide an improvedreed type valve device for supplying fuel and air mixture to thecrankcase of a two cycle engine which can be readily applied to orremoved from the crankcase for inspection without need for removing theclosure head for the crank chamber, the reed valve assemblage beinglocated in close proximity to the outside of the crank chamber.

An additional object of the present invention is to provide an improvedreed valve structure for supplying fuel mixture to the crank chamber ofan internal combustion engine which embodies a plurality of valvesassembled on a common fuel supply cage and adapted to introduce largequantities of fuel mixture to the crank case in a most effective mannerduring each admission cycle.

These and other additional objects and advantages of the invention willbecome apparent from the following detailed description.

A clear conception of the features constituting the present improvementand of the mode of constructing and of utilizing fuel supply devicesembodying the invention may be had by referring to the drawingscomprising and forming a part of this specification wherein likereference characters designate the same or similar parts in the variousviews.

FIGURE 1 is a part sectional side elevation of a typical internalcombustion engine of the fractional horsepower type embodying thepresent improvement, the section beingtaken through a portion of one ofthe cylinders, crankcase and fuel supply passage;

FIGURE 2 is a somewhat enlarged exploded perspective view of one of theimproved valve assemblages showing one of the reeds and a reed retainerand limit member about to be applied to one side of the cage;

FIGURE 3 is a similarly enlarged side elevation of one of the improvedreed valve assemblages; and

FIGURE 4 is a section of the reed valve assemblage taken along the line44 of FIGURE 3.

While the invention has been shown and described herein as beingparticularly applicable to one type of fractional horsepower internalcombustion engine of the two cycle type, it should be understood that itis not intended to unnecessarily restrict the invention by virtue ofsuch limited embodiment; and it is also understood that certaindescriptive terms used herein shall be given the broadest possibleinterpretation consistent with the disclosure.

Referring to the drawing, the typical fractional horsepower internalcombustion engine shown comprises, in general, a fuel inductioncrankcase 6 forming a housing for a crank 7 carried by the main shaft 8which is journalled in bearings 9 and projects outwardly away from theopposite sides of the crankcase; a cylinder 1t secured to the crankcase6 and having therein a piston -11 rcciprocable in the central plane 12of revolution of the crank, and which is drivingly connected to thiscrank by a connecting rod 13; and an improved fuel supply deviceassociated with the crankcase 6 remote from the cylinder M forintroducing successive charges of fuel mixture into the crankcase andcylinder during normal operation of the engine.

One outwardly projecting portion of the crankshaft S is provided with afly-wheel l and with engine starting mechanism confined within a housing16 supported from the crankcase 6, while the opposite outwardlyprojecting portion of this shaft 8 may be connected to a variety ofappliances which are to be driven by the engine. The interior of thecrankcase 6is communicable with the interior of the cylinder through aside fuel supply port 17, and the opposite side of this cylinder isprovided with an exhaust port 18 communicable with a spent gas receivingand discharge casing 19, while the intermediate end portion of thecylinder is provided with the usual charge ignition spark plug 20.

The improved fuel supply device constituting the gist of the presentinvention, preferably comprises a hollow polygonal fuel mixture supplycage 22 bounded by external approximately parallel side surfaces 23 andby an external transverse end surface 24- and being provided withoutwardly directed fuel passages or openings 25, 26 terminatingrespectively at the surfaces 23, 24; and a flexible reed valve 27swingable outwardly away from each of said surfaces and coacting withthe adjacent openings to control the flow of fuel therethrough into thecrankcase 6.

When the device is installed the interior of the cage 22 should be inopen communication with a carburetor 28, and the end of this cageadjoining the carburetor may be provided with an external flange 29adapted to be clamped against a hollow adapter fitting 30 and secured tothe crankcase 6 by cap screws 31, as shown in FIGURE 1, it beingunderstood that the adapter fitting may be formed as an integral part ofthe crankcase. The fuel delivery portion of the cage 22 will then beentirely within the fitting 30 but closely adjacent to the crankcaseinterior, with the side cage surfaces 23 disposed approximately parallelto the plane 12 and the end surface 24 approximately perpendicular tothis plane.

Each of the reed valves 27 is also preferably provided with an arcuatestop 33 secured to the adjacent cage surfaces 23, 24, and these stopslimit the swinging move ment of the reeds and prevent the valves 27 fromstriking the interior of the fitting 30 or the interior of the crankcaseand from swinging into the path of the crank 7. The valves 27 and stops33 may be formed singly or in pairs as shown in FIGURE 2, and arefastened to the cage 22 by screws 34. Suit-able leakage preventinggaskets may be interposed between the cage flange 29 and the carburetor28 and fitting 30, and the cap screws 31 permit convenient attachment orremoval of the valve cage 22 while the screws 34 permit like applicationor replacement of the valves 27.

When the improved internal combustion engine has been constructed andassembled as shown in FIGURE 1, and has been applied to the appliancewhich is to be driven or actuated, the engine may be placed in operationwith the aid of the starter confined within the casing -16 in a wellknown manner, whereupon the reciprocating piston 11 will alternatelydraw successive charges of fuel mixture from the carburetor 28 past thereed valves 27 into the crankcase 6 and after being compressed withinthis crankcase the charges enter the cylinder 10 through the inlet port.The piston 11 thereafter compresses the admitted fuel charges which aresubsequently ignited by the spark i plug 20 to apply power to the crank7 through the cylinder outlet port 18 into the exhaust casing 19.

While all of this functioning of the engine is old and well known, it isimportant to introduce fuel charges of maximum volume to the crankcase 6during each induction stroke, and such action is effected by providingnumerous well distributed but relatively small inlet openings 25, 26 andvalves 27 in the polygonal cage and by directing the entering fuelstreams approximately parallel to the direction of reciprocation of thepiston 11 in the plane 12 as well as in a direction laterally thereto.This assemblage causes least resistance to the flow of the fuel mixtureand therefore insures a full charge during each suction stroke, andwhile the polygonal cage 22 has been shown as having square transversecross-section, a greater or lesser number of flat side surfaces 23formed with openings 25 may be provided without departing from thepresent invention.

The provision of fiat bounding surfaces is preferred in order to permittight closing of the reed valves, and the cage 22 should also be of suchlength that the valves 27 will not swing into the path of the revolvingcrank 7, while the stops 33 effectively limit the opening movement ofthese valves. With the introduction of maximum charges of fuel mixturethe engine will obviously operate at high speed with maximum volumetricefiiciency, and the invention is advantageously applicable to single andmultiple cylinder internal combustion engines.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. For use in an internal combustion engine having a fuel inductioncrankcase housing a crank operatively connected to and revolvable in thecentral plane of an engine piston, a substantially cubical fuel mixturesupply device having several fuel inlet openings communicable throughthe side walls thereof with the crankcase, said inlet openings beingbounded by adjacent surfaces disposed respectively approximatelyparallel and perpendicular to said plane, and a reed valve swingableoutwardly away from each of said surfaces and coacting with the adjacentopening to control the flow of fuel therethrough into said crankcase.

2. For use in an internal combustion engine having a fuel inductioncrankcase housing a cnank operatively connected to and revolvable in thecentral plane of an engine piston, a polygonal fuel mixture supply cagehaving opposite sides and an end outwardly directed fuel inlet openingscommunicable with the crankcase and bounded by adjacent surfacesdisposed respectively approximately parallel and perpendicular to saidplane, and a reed valve swingable outwardly away from each of saidsurfaces and coacting with the adjacent openings to control the flow offuel therethrough into said crankcase.

3. For use in an internal combustion engine having a fuel inductioncrankcase housing a crank operatively connected to and revolvable in thecentral plane of an engine piston, a polygonal fuel mixture supply cagehaving fuel inlet openings in four sides and an end thereof allcommunicable with the crankcase, said side openings being bounded byadjacent surfaces disposed approximately parallel to said plane and saidend opening being bounded by an adjacent surface disposed approximatelyperpendicular to said plane, and a reed valve swingable outwardly awayfrom each of said surfaces and coacting with the adjacent openings tocontrol the flow of fuel therethrou-gh into said crankcase.

4. For use in an internal combustion engine having a fuel inductioncrankcase housing a crank operatively connected to and revolvable in thecentral plane of an engine piston, a hollow substantially cubical fuelmixture supply device having fuel inlet openings communicable throughthe side walls thereof with the crankcase, said inlet openings beingbounded by adjacent surfaces disposed approximately parallel andperpendicular to said plane, and a reed valve swingable outwardly awayfrom said surface and coacting with the adjacent opening to control theflow of fuel therethrough into said crank- 5 case, said reed valve eachhaving an arcuate stop plate associated therewith to limit its outwardswing.

References Cited in the file of this patent UNITED STATES PATENTS2,420,056 Seligmann 61328.1. May 6, 1947 10 6 Kiekhaefer May 26, 1953Kireher et a1. Jan. 24, 1956 'Morgenroth Jan. 29, 1957 Jasper Feb. 26,1957 Norton Apr. 26, 1960

